1. Field of the Invention
The present invention relates to a cam mechanism which is incorporated in a photographing (imaging) lens (lens barrel) such as a zoom lens of a camera. More particularly, the present invention relates to a cam mechanism having a cam ring for moving a linearly movable member by rotation of the cam ring.
2. Description of the Related Art
Miniaturization of lens barrels incorporated in optical devices such as cameras has been in increasing demand. In retractable lens barrels which advance and retract by rotation of a cam ring, it is desirable to reduce the length of the cam ring while securing a sufficient range of movement of each movable lens group in an optical axis direction, and also it is desirable to reduce the size of the cam ring while insuring the accuracy of travel of each movable lens group.